December 21, 2015

When total strangers meet…

Click on any image to see a larger version

What can you possibly expect when hooking up a camera, a lens and some accessories that were never intended to even meet? It would be rather foolish to presume that their individual designers worried for a moment about possible incompatibilities and unwanted interactions…

And yet, once in a while, the unexpected happens and you’re left with an intriguing combo to explore and enjoy!

Stage left: the Fujinon Teleconverter XF 1.4x TC WR

Last October, Fujifilm announced a 1.4x teleconverter adapter, a high-quality and high performance optical accessory that multiplies the focal length of the attached lens by 1.4x. As the imaging circle is enlarged (its surface area doubles) there is a one stop loss of light transmission. A series of firmware updates for the various X-bodies ensures that the recorded EXIF information reflects the actual aperture and focal length when the TC is used.

A 1.4x crop may not seem much, but all help is welcome with a 16Mpx sensor…

The combination of the 1.5x APS-C sensor crop factor and the 1.4x TC magnification results in a final ‘35mm FF equivalent’ focal length of 2.1x the original lens value.

At this moment, the XT 1.4x TC can only be used with the XF 50-140mm f/2.8 zoom. The combo becomes a 70-196mm f/4 zoom lens (covering the same angle of view as a full-frame 105-294mm lens). We can however expect additional compatibility with the XF 100-400mm super-tele zoom and XF 120mm macro lenses that will challenge our lens lust (and bank accounts) sometime during 2016.

The XF 1.4x TC sitting where it currently belongs: behind an XF 50-140mm tele zoom

There are countless reviews documenting how well the TC 1.4x/50-140 combination performs optically. Suffice to say that my own quick-and-dirty tests fully confirm this.

100% center crops with and without the 1.4x TC (click on image for larger version)

Besides any possible optical considerations, it is physically impossible to mount the TC to any other current XF lens. The front part of the TC extends significantly forward from the lens mount, and requires some ‘opens space’ at the back end of the to-be-mounted lens. Obviously, the design of the XF 50-140mm accommodates for this (and so will – at least – two of the future ones) but none of the other available XF lenses will work…

Now, if any other lens came with both an XF mount AND sufficient open space at the back to receive the TC’s protrusion, would it then be possible to make use of the teleconverter…?

Stage right: an adapted legacy lens

When I first saw images of the XF 1.4x TC and noticed its unusual shape (compared to traditional TC designs), I vaguely remembered a post I stumbled upon a few months earlier on a Micro Four Thirds forum. The Olympus M.Zuiko MC14 indeed has a very similar construction.

Ever since acquiring a Fujifilm X-Pro1 in early 2012, I have used a number of F-mount lenses collected over 40+ years of shooting with Nikon SLRs and DSLRs. In case you are interested: more info on this introduction to adapted lenses, and this full overview of Metabones adapters.

A mount adapter enables the use of ‘legacy’ lenses on recent system camera bodies. The classic (D)SLR design requires a fairly large flange (i.e. film/sensor-to-lens mount) distance to make room for the reflex mirror box. With mirrorless cameras, the lens mount sits a lot closer to the sensor. A basic lens adapter compensates for the difference by providing additional spacing between the respective lens mounts. For a Nikon F to Fujifilm X mount adapter, that distance must be exactly 28.8mm.

The above image clearly shows that the (otherwise hollow) adapter provides ample space to accommodate the TC’s extending front section. Once the adapter is attached, the TC sits well behind the F-mount and does no longer requires a specific lens construction.

Obviously, there will be no electrical communication possible between lens and camera body, and we will not have any actual lens and aperture information embedded in the EXIF data. Nothing different here compared to the ‘regular’ use of such a lens adapter. However, metering in A and M modes as well as all forms of manual focus assistance remain fully operational. Great to discover that a camera-with-TC does not get confused when no XF lens is attached!

Solving the mechanical compatibility of course does not guarantee that we can expect a great or even acceptable optical performance. We are combining components that were originally designed for use in totally different circumstances. I don’t know of any teleconverter design that was not optimized for a specific and limited range of (mostly tele) lenses. And I am pretty convinced that none of the Fujifilm engineers even for a brief moment worried about such an exotic line-up!

With that in mind, I was more than curious to have a look at my first test images. All ye who enter here, abandon hope…

First test: some ‘normal’ primes

I honestly did not have any expectations at all for this initial quick assessment. We all know that TCs are traditionally intended for use with tele lenses. So why even bother to snap on a cheap mid-80’s Nikon AF 50mm f/1.8 (pre-D) and a slightly more recent Nikon AF-D 85mm f/1.8?

Surprise!

Have a look at these images and 100% center crops, shot in my familiar light tent studio, at distances around 70cm resp. 100cm. For all of the comparison shots following, both versions have been processed with identical Lightroom settings. (click on any image for a larger version)

Nikon AF 50mm f/1.8 with XF 1.4x TC

100% center crops with TC, at f/1.8 resp. f/4

Nikon AF-D 85mm f/1.8 with XF 1.4x TC

100% center crops with TC, at f/1.8 resp. f/4

With a little stopping down, you get perfectly useable image quality (remember for exposure calculation that with the TC the actual aperture is one stop slower than set on the lens). No visible signs of vignetting or aberrations, in fact a very similar optical performance as the original ‘naked’ lens.

As the available range of Fujifilm XF lenses grows (with some additional gap fillers from third parties), my regular use of adapted lenses has substantially diminished. Except for a few ones, for which there are still no alternatives with an X-mount. So let’s have a look at two more legacy primes that frequently find themselves onto my X cameras.

Second test: a trusted macro lens

I bought a Tamron 90mm f/2.8 SP Di Macro lens (with Nikon F-mount) in 2004, and have used it extensively ever since. It is an extremely sharp lens, that offers a generous working distance even at extreme close-up range. The longer focal length, the 1:1 capability and the generous manual focus ring are three reasons for giving it ample show time next to my beloved XF 60mm. The only X-mount alternative is the Samyang 100mm f/2.8 Macro, but that one does not offer enough value added to consider a switch. So, for now the Tamron 90mm it is (until perhaps I give in to the XF 120mm?).

If this lens would still perform in combination with the XF 1.4x TC, it would bring an increased 1.4:1 magnification without sacrifying shooting distance.

The Tamron 90mm f/2.8 SP Di Macro ready for action

I will let you be the judge on the results of a quick macro test. I used reasonable care to make good shots (solid tripod, manual focus assist, electronic remote, self timer…) without spending too much effort. My subject was a 29mm x 25mm postage stamp; the actual width of the word ‘BELGIË' is 7.5mm, the circle around the ‘1’ has a 4mm diameter. As always, clicking on an image presents a larger version in a separate window.

Full image without TC

Full image with TC

100% center crops compared

There is a little loss of micro contrast, requiring nothing more than a small nudge to the Clarity slider. No sign of visible vignetting or serious corner sharpness degradation. My conclusion: whenever I hit the need for the extra magnification, I will not hesitate to put the XF 1.4x TC behind this lens!

I also did a quick test on a distant subject (about 150m from my shooting position):

Full image without TC

Full image with TC

100% center crops compared

A nice result as well.

Third test: a classic tele

I have always liked Nikon’s AF-D 180mm f/2.8 IF ED. I owned a neat second hand copy, sold it later (as I felt I wasn’t using it often enough on my D700) but ended up acquiring another used copy, one in even better condition. This medium tele lens is tack sharp even fully open, and has a nice micro contrast.

The 180mm + TC on an X camera delivers an angle of view close to a 400mm f/4 lens on a full-frame body. As expected, a stopping down 1 or 2 stops and adding a little Clarity leads to more than acceptable results. At f/2.8 this lens shows visible chromatic aberration; adding the TC makes it a little worse; by f/5.6 it is already significantly reduced. Again, nothing that Lightroom cannot easily correct for.

I next pointed my camera towards a subject at medium distance (some 25m):

Finally, I was curious about the close-up performance of the 180mm + 1,4x TC combination. I took the following shots from about 1m distance:

Full image without TC

Full image with TC

100% center crops (without and with TC) compared

Conclusion – and why bother?

All of the above is far from a stringent, carefully controlled optical test. Frankly, the whole idea of using the XF 1.4x TC in combination with an adapted legacy lens is a bit ‘exotic’ to begin with… and therefore perhaps not worth much more effort J

My experiments indicate that more than reasonable image quality can be obtained with a broad range of non-Fujifilm lenses. That by itself is a remarkable outcome, and probably points at a very ‘robust’ optical design of the teleconverter. If true, that offers the perspective for many more useful (and designed for) lens combinations in the future. How about that?

Beware to extrapolate my findings to any other TC/lens combinations! Please do realize that any decent result is nothing more than a collateral by-product of the TC ‘s design targets.

If you happen to own an XF 1.4x TC, as well as some legacy lenses and an adapter with sufficient physical depth, please go explore! You may discover a handy stopgap solution here and there, while we wait for an even more complete XF lens line-up. I have little doubt that I will still use these legacy lenses once the 120mm macro and a 100-400mm tele zoom become available (and part of my glass collection): in the long term autofocus and image stabilization will prevail, even when coming at the cost of one f-stop or so. But until then…

So why again do we even bother testing these weird combinations? Because we can, of course, and because it’s a lot of fun as well!

August 11, 2015

Pimp your XF lenses!

Thanks for the many comments and suggestions! I have (twice now) updated this post with a quick overview table (at the end), and added a few clarifications here and there.

Click on any image to see a larger version

Let’s be honest: next to the ease-of-use of the Fujifilm X cameras, the advantages of their sensor, the performance of the XF glass and the resulting image quality, many X-shooters just love the retro design and handling of the bodies. Right from the start, with the original X100, we got a compact tool to completely enjoy taking pictures. If you’re old enough to have started photography with roll film or 35mm cassettes: just add “again” at the end.

In order to augment the “old days” experience, we’ve been adding leather carrying and wrist straps, half cases, thumb grips, soft releases, old-fashioned cable releases… In the end though, you can’t but ask yourself:

Why didn’t Fujifilm bring us sexier lens hoods?

It started rather well actually. The X100’s fixed 23mm lens comes with a nice metal vented release. That comes handy when using the optical viewfinder, as less of the field of view is obstructed (as long as the openings are well aligned, hence the bayonet mount).

Then, the XF 18mm f/2.0 and XF 35mm f/1.4 (both part of the X-Pro1 release wave) came with somewhat classy rectangular metal hoods, alas also with horrible rubber front caps.

After that, sadly, we saw the typical petal shaped or (rather oversized) cylindrical lens hoods coming over from the (D)SLR market…

There’s a lot of good things to say about the Fujifilm lens hoods though. They do come included with the lenses, and provide more than adequate light shielding and protection for the front lens element. They can be mounted reversed to save space in your bag, and are made of solid mass-colored plastic to resist dents and scratches (the 18 and 35 metal ones are the exception for both last attributes).

But they remain cumbersome, tend to come off or knock loose when banging around in crowds, are a pain to mount/unmount when changing lenses, and look quite a bit, well… boring.

It’s not all that bad, is it?

Fortunately, there are plenty of alternatives available. Some come from traditional third party accessory brands, others spawn out of Chinese workshops courtesy of eBay.

As I was gradually building up my lens collection for the X-cameras, I constantly looked for and experimented with alternative and mostly classic-styled lens hoods. The ones that I have and use are all sturdy one-piece metal designs, with a screw mount in the matching filter thread size. Screw-on hoods have the advantage that they stay firmly in place even when things go hectic around your camera. Read: street photography, event coverage, reportage…

These hoods are anodized black, with a satin finish on the outside and a grooved matte finish on the inside, the latter to reduce internal reflections. They have proven to resist well against dents and scratches, I cannot see much wear other than along the front outer rim: in that they perform at least as well as any other metal hood I used throughout the (many) years.

As you can see above, the hoods come in different versions, each available in various sizes:

I order my lens hoods directly from Hong Kong based eBay vendor gadgetworldexports. They have proven to be very reliable, supplying correct information, and offering free and fast standard shipping (about twice as fast to Belgium as any other HK/China outlet I ordered from). Never had any issue whatsoever.

After a lot of small yellow packages in the mailbox, I now have a broad collection in thread sizes from 39mm to 72mm (the ‘xx’ in the model designation). Unit prices ran between USD 3.49 and USD 5.99, shipping included – so nothing to break the bank. No fear for damaging or losing.

* A keen observer on some of the images that one of the vented hoods shows not three but five “vents”. The very first vented hood I purchased (early 2012, a 52mm model to go on the XF35) indeed came from a different eBay vendor and has a slightly different design.

More form than function

I don’t want you to get all carried away, now… Remember that the length of any symmetrical lens hood should not exceed the minimum depth of the Fujifilm petal hoods, or else corner vignetting may pop up (after all, that’s what the originals were dimensioned for).

Also, whereas screw-on filters can be added without changing the position of a bayonet mounted hood, they will take up space between the lens thread and the screw-on lens hood: that too may lead to vignetting. Take this into account when combining screw-on hoods with screw-on filters!

Finally: you can put lens caps on the hoods for extra dust or impact protection, e.g. inside a carrying bag. I recommend to use appropriately sized snap-on or pinch-type caps attaching to the front of the hoods. Such caps are readily available from various sources, including the eBay vendor I use. You can even ‘re-assign’ some of the supplied Fujifilm caps from one lens to another (e.g. use the 52mm cap from the XF18 or XF35 with a 39mm vented hood). The quick overview table at the end of this post lists the required cap sizes.

Some people may prefer to use the supplied Fujifilm cap by mounting it deeper inside the hood. Installation and removal however becomes cumbersome, takes time and requires proper care. The vented hoods perfectly accept the original caps: they get to sit halfway into the hood, past the vents, so the space immediately in front of the lens is sealed off. I found that the wide hoods simply will not adequately hold the caps. With cylindrical hoods, the caps fit but do not stay firmly in place. In addition, inserting or removing the cap may scratch the grooved interior, potentially exposing bare metal and causing reflections. Therefore I prefer using front-mounted caps with both wide and standard or tele hoods.

Enough caveats: let’s have a closer look at my choices and findings for the various XF lenses.

Very wide primes – 14mm & 16mm

Only one viable choice here, the wide model, as a vented hood will cause vignetting in the corners of the frame. Required thread sizes are 58mm (XF14) and 67mm (XF16).

The lens+hood combo is shorter than with the Fujifilm shades, but wider at the front. That is not am issue with my (ThinkTank Retrospective) camera bags. The front lens element remains adequately protected. And the whole screams power!

Wide primes – 18mm & 23mm

Here I prefer the vented variants (thread sizes 52mm and 62mm respectively). The lenses now take on the look of their classic counterparts and the overall bulk is reduced, especially with the 23mm. Have a look at my preferred street shooter setup:

Standard primes – 27mm & 35mm

This time we get some choices. The XF27 looks great with a vented hood, but a standard cylindrical one will no doubt do as well (39mm thread). But in this case ANY hood will defy the compact pancake nature, so mine usually goes out ‘as is’: bare naked.

The XF35 then looks great with both the vented model and the standard design (52mm thread). The decision becomes a matter of taste (and mood): I find myself alternating…

Short tele primes – 56mm & 90mm

My preference goes towards the sleek look of a cylindrical hood. Both the standard and the tele sizes will do on either lens, so I decided to split my options. Kudos to Fujifilm for the common 62mm thread size!

Don’t you agree that the 56mm looks quite ‘sharp’ on the outside as well in this ‘dress’?

What about the 60mm macro?

Good question. My XF60 doesn’t venture outdoors a lot, I mainly use it for product and close-up shots in the studio, where the default lens hood does well. Furthermore, the lens is known not to like stray light. If you find the original Fujifilm hood too large, be aware that the Fujifilm bayonet shade for the XF35 fits equally well (above right).

A vented hood with 39mm thread is another option, without disturbing the autofocus operation (something the XF60 is notorious for). I am sure a standard cylindrical hood would work too, I just never got one of those in 39mm thread (yet).

The ‘convenience’ zooms – 18-55mm, 18-135mm & 55-200mm

It’s a bit of a stretch to strive for a classic look with zoom lenses, but al least the XF18-55 is compact enough to pass for a longer prime – as long as you drop the default petal shade. And although my primes see ‘action’ more often, I do use my lighter zooms in similar situations, where a screw-on lens hood will stay on solidly and provide better physical protection.

My choices went towards a vented hood for the XF18-55 and XF-18-135 (58mm and 67mm threads respectively), and for a tele cylindrical one on the XF55-200 (62mm thread). Again, the resulting combination is more compact than with the Fujifilm hoods.

The ‘serious’ zooms – XF10-24, XF16-55 & XF50-140

These excellent lenses come with a heft that in no way you can ‘camouflage’ as a prime… Also, in my case, those are the optics I go to for ‘serious’, more deliberate, top quality work. So here I prefer to stick with the original Fujifilm lens hoods, that provide good shielding against stray light across the zoom range, and – when mounted in reverse – take up little extra space in the bag.

Anyway, I doubt that the XF10-24 would stay free of corner vignetting even with a wide model hood, looking at the minimum depth of the original shade. So I did not even order an alternative in 72mm thread (yet). Same for the XF16-55, where in addition a wide hood would considerably add to the already significant 77mm front diameter.

The only exception: the XF50-140. Here, a tele cylindrical hood (72mm thread) works just fine and – as with the 56 and 90 siblings – delivers that sleek and slim appearance.

Time for a little recap

Here’s a quick overview of the models and sizes I am using with each of the XF lenses:

I have added the appropriate sizes for pinch style lens caps should you want to add these on top of the hoods, for extra (dust) protection.

Had enough of it? You bet!

Hey, guys and girls, don’t take all of this too serious! It’s only lenses and hoods, after all… Looks and style may be pleasant and fuel good discussion (preferably around a table, after a shoot!), but none of that pimping will improve your skills or get you better images.

So, take away from the above whatever you like, and keep up the good photo fun!

July 28, 2015

Two years later: where do we stand?

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In August/September 2013, I published an extensive review of the Metabones adapters for mounting Nikon F-mount lenses onto Fujifilm X camera bodies, including the Speed Booster focal reducer model, as a series of eight blog posts:

This July 2015 update covers some relevant developments since that time.

Speed Booster ULTRA: improved optical performance

In September 2014, Metabones announced an ULTRA version of its APS-C Speed Booster models with a new optical design - 5 elements in 4 groups - incorporating ultra-high index tantalum-based glass to achieve improved corner sharpness, distortion and reduced vignetting.

The original Metabones Speed Booster, announced in January 2013, counted 4 elements in 4 groups. Both versions share the same 0.71x magnification, and so reduce the crop factor of Fuji X-mount cameras from 1.5x to 1.07x.

The new optical formula significantly improves corner sharpness and reduces vignetting when using lenses with a longer exit pupil distance, such as ultra-high speed (f/1.2 and below) primes and pro-grade f/2.8 zooms.

Simply stated, the exit pupil is the virtual image of the aperture stop as seen from behind the lens. The distance between the exit pupil and the sensor plane determines the range of angles of incidence of the light rays hitting the sensor. The closer the exit pupil to the sensor, the higher the angles of incidence at the edges of the field, and the higher the risk for pixel vignetting. Note that exit pupil distance and focal length are completely unrelated: all depends on the specific optical design.

Most classic SLR lenses have an exit pupil distance in the 50-90mm range. The original Speed Booster gives excellent results with exit pupil distances up to 100mm. The ULTRA extends the exit pupil range out to about 150mm, and delivers visible improvements from about 90mm onwards. Popular Nikon lenses that will benefit from this include the AI-S 50mm f/1.2, the AF-D 105mm f/2.8 Micro and the ‘holy trinity’ zooms (AF-S 14-24mm f/2.8G, AF-S 24-70mm f/2.8G and AF-S 70-200mm f/2.8G VR types I & II).

All N/F-X adapters: improved aperture control mechanism

One review section, The Metabones approach to aperture control, dealt with the operation of the aperture ring available on some adapter models - including the SpeedBooster version - to control the shooting aperture when using G-type lenses (the ones that don't come with their own aperture ring).

As noted in the review, the original mechanism does not provide a linear control action: (half) steps on the aperture ring do not correspond to equally spaced changes in the lens aperture. This significantly complicates the process of manually setting a precise aperture value.

With the release of the SpeedBooster ULTRA version, Metabones has changed the aperture control mechanism and the control ring marking on both the Speed Booster ULTRA and the ‘glassless’ Nikon-F-to-Fuji-X adapter. The image below shows the original version of the latter at left, and the updated version at right.

It is immediately clear that the aperture scales have changed. For some reason, the lettering moved from ‘F-2-3-4-5-6-7-8’ to ‘F-1-2-3-4-5-6-7’. Perhaps this is an attempt to more clearly indicate the amounts of f-stops down from the fully open aperture position (but, as we will discover, that doesn’t hold…)?

The original version has 15 well-defined click stops. The revised version no longer has discrete click stops, no doubt to facilitate the continuous aperture changes desired by videographers. The unit however is shipped with the necessary extra hardware parts to ‘install’ a click system should the user so desire (instruction videos are available on YouTube).

More importantly, Metabones radically changed the mechanism that drives the aperture control lever at the back of a Nikon F-mount lens. The original rotating actuator is replaced by a sliding tab, that provides the linear motion AI-S and later Nikon lenses expect: the aperture lever travels the same amount for every f-stop.

old at left, new at right

The difference in operation is best shown by this stop-motion animation:

old above, new below

I had the opportunity to have a thorough look at the new design, as one of my friends kindly loaned his copy (thanks, Wim!).

I measured the effect of the adapter’s aperture ring position on the lens aperture using both the old and the new Metabones adapters, using four prime lenses (Nikon 50/1.4, 50/1.8 and 85/1.8 AF-D’s, and my trusted Tamron 90/2.8 macro), with the following result:

Note that some of the jitter of the ‘new’ curves may come from the fact that it now is harder to precisely set (or repeat) an aperture value, due to the now click-less control ring.

After averaging each set of curves, we find the following:

It is more than clear that the new aperture control design results in an almost perfectly linear action, with a maximum of about 6 f-stops down from the fully open value (which of course depends on the attached lens). There is still the half-stop ‘loss’ at the beginning of the curve.

The linear behavior makes it a lot easier to work with G-type lenses (without aperture ring). Of course, I still prefer shooting with older lenses that have their own aperture ring.